Key Points• Single subcutaneous dosing of ACE910 has a linear PK profile, a half-life of 4 to 5 weeks, and FVIII-mimetic procoagulant activity in humans.• ACE910 at doses up to 1 mg/kg is well tolerated and has no notable adverse hypercoagulable effect in healthy Japanese and white adults.ACE910 is a recombinant humanized bispecific antibody that binds to activated factor IX and factor X and mimics the cofactor function of factor VIII (FVIII). This first-in-human study examined the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of ACE910 in healthy male adults. A total of 40 Japanese and 24 white subjects were randomized to receive a single subcutaneous injection of ACE910 (Japanese: 0.001, 0.01, 0.1, 0.3, or 1 mg/kg; white: 0.1, 0.3, or 1 mg/kg; n 5 6 per dose group) or placebo (n 5 2 per dose group). ACE910 exhibited a linear PK profile and had a half-life of ∼4 to 5 weeks. In FVIIIneutralized plasma, ACE910 shortened activated partial thromboplastin time and increased peak height of thrombin generation in a dose-dependent manner. All adverse events were nonserious and did not lead to any subject's withdrawal. Neither clinical findings nor laboratory abnormalities indicating hypercoagulability were observed. Two of 48 subjects receiving ACE910 (1 Japanese and 1 white) were positive for anti-ACE910 antibodies (antidrug antibodies [ADAs]). One subject tested positive for ADAs both before and after ACE910 administration, whereas the other became ADA positive after receiving ACE910. The PK and PD profiles of ACE910 were similar in healthy Japanese and white subjects and suggest that ACE910 will be an effective and convenient prophylactic treatment of hemophilia A. This trial was registered at www

BackgroundEmicizumab (ACE910) is a bispecific antibody mimicking the cofactor function of activated coagulation factor VIII. In phase I–I/II studies, emicizumab reduced the bleeding frequency in patients with severe hemophilia A, regardless of the presence of factor VIII inhibitors, at once-weekly subcutaneous doses of 0.3, 1, and 3 mg/kg.MethodsUsing the phase I–I/II study data, population pharmacokinetic and repeated time-to-event (RTTE) modeling were performed to quantitatively characterize the relationship between the pharmacokinetics of emicizumab and reduction in bleeding frequency. Simulations were then performed to identify the minimal exposure expected to achieve zero bleeding events for 1 year in at least 50% of patients and to select the dosing regimens to be tested in phase III studies.ResultsThe RTTE model adequately predicted the bleeding onset over time as a function of plasma emicizumab concentration. Simulations suggested that plasma emicizumab concentrations of ≥  45 μg/mL should result in zero bleeding events for 1 year in at least 50% of patients. This efficacious exposure provided the basis for selecting previously untested dosing regimens of 1.5 mg/kg once weekly, 3 mg/kg every 2 weeks, and 6 mg/kg every 4 weeks for phase III studies.ConclusionsA pharmacometric approach guided the phase III dose selection of emicizumab in hemophilia A, without conducting a conventional dose-finding study. Phase III studies with the selected dosing regimens are currently ongoing. This case study indicates that a pharmacometric approach can substitute for a conventional dose-finding study in rare diseases and will streamline the drug development process.Electronic supplementary materialThe online version of this article (10.1007/s40262-017-0616-3) contains supplementary material, which is available to authorized users.

Emicizumab (ACE910) is a bispecific antibody that is a novel, subcutaneously injectable treatment for patients with hemophilia A. This study assessed the relative bioavailability of emicizumab between old and new drug products (DPs) and among 3 commonly used subcutaneous injection sites (abdomen, upper arm, and thigh), together with its absolute bioavailability in healthy volunteers. Forty-eight healthy volunteers were randomized into 4 groups to receive a single subcutaneous injection of 1 mg/kg with the old or new DP, and another 12 volunteers each received a single, 90-minute, intravenous infusion of 0.25 mg/kg with the new DP. Similar pharmacokinetic profiles were observed between the DPs, with geometric mean ratios of 1.199 (90% confidence interval [CI] 1.060-1.355) for the maximum plasma concentration and 1.083 (90% CI 0.920-1.275) for area under the plasma concentration-time curve extrapolated to infinity. The geometric mean ratios of maximum plasma concentration and area under the plasma concentration-time curve extrapolated to infinity for upper arm versus abdomen were 0.823 (90% CI 0.718-0.943) and 0.926 (90% CI 0.814-1.053), respectively, and those for thigh versus abdomen were 1.168 (90% CI 1.030-1.324) and 1.073 (90% CI 0.969-1.189), respectively. Absolute bioavailability ranged from 80.4% to 93.1%. These results suggested that no emicizumab dose adjustment would be needed when switching the DPs or injecting to different sites interchangeably and that emicizumab injected subcutaneously is highly bioavailable.

A population pharmacokinetics model of erlotinib was developed and validated in Japanese patients. There was no relationship between exposure of erlotinib before the occurrence of ILD-like events and the occurrence of ILD-like events when erlotinib was administered at the same dosage. The high plasma concentration of erlotinib reported in patients after the onset of ILD-like events may be explained by CL/F decrease which occurs along with increasing levels of AGP which was identified as a covariate for CL/F.

No abstract